Sunday, 9 August 2015

Planning the analysis of half a kilometre of African lake mud...by Jonathan Dean

Jonathan Dean is a Postdoctoral Research Assistant working the Stable Isotope Lab at the British Geological Survey, and here he introduces the new project he is involved with: analysing sediments from Ethiopia.

In the end of June, around 20 scientists from the UK, Germany and the US met at the University of Cologne to discuss our new project: the analysis of half a kilometre of sediments taken from Lake Chew Bahir in Ethiopia. We aim to use the sediments to reconstruct how the environment of east Africa has changed over the last 500,000 years.

Scientists from the UK, Germany and the US are involved in the project

We are particularly interested in how the climate changed during the time our species Homo sapiens, has existed: the last 200,000 years or so. We want to understand whether climate changes could have encouraged our evolution and ultimately our migration out of Africa to populate the rest of the world. Because no such long-term records of past climate change from this era have been produced before, ideas linking climate and human evolution have so far been mostly speculative.

Chew Bahir when the lake sediments were being drilled in November 2014 (Photo: Julian Ruddock)

The sediment cores were taken in November 2014 from the dried-out lake basin and we started to take samples from them in a laboratory in Minneapolis in April (see GeoBlogy: Ancient links between climate and vegetation). At the meeting in Cologne, we planned how analyses will be undertaken over the next year, with some people in the group working to date the sediments to work out how old each section is, and some analysing how the chemical composition has varied in order to reconstruct how the climate changes over time. My job is to look at how the ratio of one type of oxygen to another changes in the core, which will help us to understand how the climate has changed through time from wet to dry.

More information is available on our website and a video of the project by our 'artist in residence', Julian Ruddock from the University of Aberystwyth can be viewed here.